


The Infinitesimal Calculus of Byleth Eisner

by lesbianryuko



Category: Fire Emblem Series, Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - College/University, Alternate Universe - Modern Setting, First Kiss, Flirting, Fluff, Getting Together, M/M, Male My Unit | Byleth, Male My Unit | Byleth/Claude von Riegan, Pining, Tutoring, gay people..., this will most likely be my last studentleth fic but i am still fond of this <3
Language: English
Status: Completed
Published: 2020-11-17
Updated: 2020-11-17
Packaged: 2021-03-10 05:20:41
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,603
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27598130
Author URL: https://archiveofourown.org/users/lesbianryuko/pseuds/lesbianryuko
Summary: Claude asks Byleth to tutor him in calculus. He doesn’t actually need the help, but Byleth doesn’t need to know that.
Relationships: My Unit | Byleth/Claude von Riegan
Comments: 13
Kudos: 67
Collections: Claudeleth Zine





	The Infinitesimal Calculus of Byleth Eisner

**Author's Note:**

> hi!! this was written for the [claudeleth zine](https://twitter.com/ClaudelethZ)!
> 
> as i said in my tags, this will probably be my last foray into writing studentleth, but i had a lot of fun writing it and working with everyone!
> 
> [claude voice] ahaha!! you've fallen for my scheme!! my scheme to...get to know you better :-)

“Out of time already?” Professor Hanneman says, shaking his head at the clock on the wall as if cursing the passage of time. “Well, I suppose that concludes today’s lecture. Remember, next class is our first test of the semester!”

Most of the students groan. Claude is already mentally checking out; he’s good at math, and it’s not like this class is particularly difficult. Sure, it’s not _basic_ math, but it’s still a 100-level course that he’s only taking to fill his General Education requirements.

“A friendly reminder that if you need any help, you can come to my office hours,” Hanneman continues as students pack up their materials, “or you can take advantage of the free tutoring center on campus.” He gestures to a young blue-haired man who sits directly in front of Claude. “Byleth over here is a tutor himself; if you wish to talk with someone from our class, I’m sure he’d be happy to work with you.”

Claude perks up at that. He’s been keeping an eye on Byleth for a few weeks now, and the guy never gets less intriguing. He doesn’t speak often, but when he does, it’s almost completely devoid of emotion. His entire aura is shrouded in mystery, and Claude can’t stand to be kept in the dark—especially not by a man whose smoldering gaze and deadpan voice are enough to make Claude...curious, to say the least, in more ways than one.

At the sound of his name, Byleth grunts and clears his throat. “That’s right,” he says with a wave of his hand. “I work at the tutoring center on Tuesdays, Wednesdays, and Thursdays from three to six. Schedule an appointment with me and I can help you out.”

By the time the words are out of Byleth’s mouth, Claude has already formulated a plan. As the rest of the students start to file out of the classroom, he taps Byleth on the shoulder.

Byleth turns around, one eyebrow raised slightly. “Yes?” he says, his expression unreadable, as per usual. “Oh—you’re...Claude, right?”

Claude tries not to dwell too long on the fact that Byleth remembered his name, likely from hearing Hanneman call on him a few times. “Yep,” he says, twirling his pencil between his fingers. “So, listen. I’m not feeling too confident about this test. I take good notes, but math isn’t really my strong suit.” The lies slide past his lips with ease. “I was wondering if I could schedule an appointment with you?”

“Uh, yeah, sure,” Byleth replies, grabbing a pencil of his own. “You’ll have to do it online, though.” Reaching onto Claude’s desk, he scribbles the website link upside down in one corner of Claude’s notebook. “I’m all booked up today, but I think I still have one or two spots available for tomorrow.”

“Great, I’ll check that out then,” Claude says with a polite smile. “Thanks, man. I could really use the help.”

Byleth shrugs nonchalantly. “It’s what I do,” he says as he packs up his things and stands up, tossing his bag over his shoulder. His lips twitch ever-so-slightly, possibly his attempt at returning Claude’s smile. “I’ll see you.”

Claude watches him walk out, eyeing the quiet sort of dignity in his gait, then chuckles to himself as he stuffs his own materials into his backpack. He should probably be studying calculus; instead, he’s studying other people. It’s not like this is the first time, but it feels different somehow.

—

The next day, a Wednesday, Claude heads straight from his final class to the tutoring center, which, luckily, is only a few buildings away, in Lamine Hall. The setting sun casts long shadows on the sidewalk, and a chilly wind tears through Claude’s thin sweatshirt. It might be spring according to the calendar, but Fódlan doesn’t seem to have gotten the memo.

Claude’s only been in Lamine once or twice. Luckily, a sign on the wall in the lobby area points him where he needs to go: straight down the hall and then to his left, to a decent-sized room that mostly consists of the front desk, some couches and side tables, and a narrow hallway with several closed doors. The only other person in the room is a bored-looking girl sitting at the front desk.

After Claude signs in, it doesn’t take more than fifteen seconds for Byleth to appear at the entrance to the hallway with all the tutoring rooms. “Claude?” he calls.

When Claude stands up, Byleth waves at him. “Good to see you,” he says as he leads Claude down the hall. His facial expression barely changes, but there’s a sort of warmth in those dark blue eyes. He seems...nonjudgmental. He doesn’t seem like the type of person who would get frustrated when someone doesn’t understand something right away. He doesn’t seem like the type of person who would make assumptions about someone based solely on their appearance, their name, their culture, their country of origin. Claude doesn’t know that for certain, of course, but he’d like to think he’s a pretty good judge of character. Or maybe he’s just being optimistic.

Byleth stops about halfway down the hall and opens one of the doors into a fairly small tutoring room with a table and two chairs in the center. The whiteboard on the wall has a few equations written on it, and there are some little shelves in the corners with various books and guides for writing essays. Byleth sits down in one of the chairs without a word.

Claude takes a seat next to him and unzips his backpack. As he rummages through his materials, he looks up at Byleth through the messy strands of hair that fall into his face, trying to gauge something, anything. Byleth simply raises an eyebrow at him, which could mean a lot of things.

Claude grabs his math notebook and flips it open to one of the last pages he wrote on, then sets it down on the table.

“So,” Byleth says, “what specifically are you having trouble with?”

“Mostly derivatives,” Claude says. It’s a simple story, but he’s had it prepared. “That’s why I didn’t really ask for help at first. I was doing decent-ish until we got to this last chapter.”

“I see,” Byleth says, holding his chin with one hand like a pretentious intellectual. Claude finds it endearing. “Well, let’s take a look at this…”

And then, coolly and smoothly, as if he’s been doing this his whole life, Byleth lapses into an in-depth explanation of the hows and whys of derivatives and differentiation, circling or underlining certain phrases in Claude’s notes, drawing arrows everywhere, breaking down example problems step by step in a clean, fluid hand. And he somehow manages to do it without being boring, a feat Claude would’ve thought impossible for someone so characteristically stoic. But no—Byleth speaks matter-of-factly, punctuating his lectures with sharp words or quick pencil motions. He _enjoys_ doing this, and he clearly wants those he tutors to succeed. Claude almost feels bad for monopolizing his time. _Almost._

It doesn’t take too terribly long for Claude to start spacing out—again, not because Byleth is boring, but because Claude already knows all of this, and also because he may or may not be more focused on observing Byleth than actually listening to what he’s saying. His jawline, his slender fingers, how his hair seems so effortlessly sleek—Claude finds himself wondering what it would feel like to run his hands through that hair, to lean into Byleth’s gentle touch on his skin, to—

“Claude, are you listening?”

Claude flinches in a manner not unlike when he gets jumpscared during a horror movie. “Yeah, I’ve been listening,” he says quickly, which isn’t _completely_ a lie. He flashes a tiny smirk. “I was just a little distracted. Has anyone ever told you you have gorgeous eyes?”

Byleth shakes his head dismissively, though if Claude isn’t mistaken, he thinks he sees a tiny hint of a blush on Byleth’s pale cheeks. “If you just came here as an excuse to flirt with me, then—”

“Damn,” Claude says, putting a hand against his chest in mock offense. “Do you really think so little of me, Teach? You wound me with such accusations.”

Byleth holds a hand up. “I was just joking; I—wait, Teach?”

“Yeah,” Claude says, stretching his arms out behind his head. “You’re teaching me, aren’t you? So, you’re Teach.”

Now there’s _definitely_ a blush. “I’m just tutoring you. We’re nearly the same age!”

Claude grins. “Still, it’s fun, right?”

Byleth shakes his head again, but this time there’s a twinkle of amusement in his eyes. “Let’s just get back to work.”

Claude winks. “Aye aye, Teach.”

—

The test on Thursday goes well, as expected. Byleth actually chats him up after class, asking him how he thinks he did. Claude acts modest, of course, though he makes sure to say that he feels like their tutoring session helped—and, to be fair, it’s not like it was detrimental, reviewing the material.

Then Byleth does the most unexpected thing: he asks Claude to have lunch with him. Claude almost breaks character right then and there, before covering up his surprise with a smirk and a “What, you miss me already, Teach?”

So they grab lunch on campus together in between classes, and that’s when Claude actually starts to get to _know_ Byleth. He’s an education major—of course he is—and he’s two years ahead of Claude. He’s done quite a bit of traveling with his father and has met people from a variety of cultures, a fact that Claude pretends not to find reassuring. He still leaves most of the talking to Claude—apparently he’s only really talkative when he’s teaching—but slowly, the shroud of mystery that surrounds him starts to lift, and Claude likes what he’s finding underneath. It’s only after they part ways that he realizes he forgot to ask for Byleth’s phone number.

Over the weekend, he thinks more about Byleth than he does about calculus, though he still spends most of his time reading or studying. On Monday night, he schedules another tutoring session with Byleth for Tuesday at five o’clock.

In class, Hanneman passes the tests back by handing piles to the people in the front row, who grab their test and then pass it to the people behind them. When Byleth has the stack in his hands, Claude catches a 95 percent written on the top of Byleth’s paper—impressive. Byleth sets his test down on his desk and pauses, just briefly, at the one underneath. Claude can see it from his seat: it’s his, and it’s got a 97.5 percent written on top.

He watches the moment of realization in slow motion. In the span of half a second, Byleth _knows_ , and Claude knows that he knows.

At the end of class, Claude dashes out of the room before Byleth can get the chance to corner him. If he wants answers, he’ll have to wait until their tutoring session.

Claude arrives at Lamine almost exactly at five. Just like before, Byleth calls his name mere seconds after he signs in and sits down in the waiting area, and they end up in the same room as before, too.

It’s not until Claude has pulled out his notebook and opened it to his most recent notes that Byleth sits down next to him and says, “Why did you schedule this appointment?”

Claude should probably just come clean, but he’s curious to see how long he can keep up the ruse. “I thought you could help me again,” he replies, gesturing to the notes he took on the lecture earlier. “Since we started a new chapter.”

Byleth stares at him for a long moment, unblinking, his expression indecipherable. Finally, he says, “Claude, you only got one question wrong on that whole test. That’s better than I did.”

Claude’s cheeks start to heat up a little. “That just goes to show how good your tutoring was,” he says with a smile and a wink, but it’s clear that his scheme is nearing its end.

Byleth seems to choose his next words carefully. “Claude,” he says, his voice measured, “you didn’t need any help at all, did you?”

Claude’s first instinct, of course, is to deny. What is he supposed to say? That he wasted Byleth’s precious time to chase a fantasy, a curious whim? That he did exactly what Byleth jokingly accused him of doing? What’s _wrong_ with him?

Byleth’s face softens, just slightly, at Claude’s lack of an immediate response. “Claude…”

Claude runs a hand through his hair. His blush, he’s sure, has intensified significantly. “Alright. You caught me. I never needed the help.”

“Then why do all this?” Byleth asks. He doesn’t quite seem upset so much as baffled. “What was the goal? What do you want?”

_What do you want?_

_I want—_

To watch the world change? To fit in? To not feel like he _has_ to fit in? To walk into a room and not wonder what everyone else thinks when they look at him? To make sure no one else ever feels as alone as he has?

To be liked? To be loved?

It’s all true to some extent, but right here, right now, only one thing comes out of Claude’s mouth: “I think...I think I want _you_.”

Byleth opens his mouth, then closes it again, his cheeks starting to redden. For the first time, he looks utterly awestruck. “I...so...when I said...”

“You were right,” Claude admits. “You piqued my interest as soon as I saw you, but I guess I couldn’t find a good excuse to talk to you. Until now.”

Byleth doesn’t say anything. Claude sighs and shakes his head. He should’ve known. His silly scheme squandered something good before it could even really begin. “Look,” he starts, “I’m sorry. It was a stupid idea. I won’t talk to you anymore, and we can just forget this whole thing ever—”

He never gets to finish his sentence, because at that moment, Byleth leans forward in his chair and presses his lips to Claude’s.

It takes Claude a second to register what’s happening before he finds himself kissing back, his eyes closed. Byleth lifts his hands up to cradle Claude’s face, his long fingers surprisingly tough against Claude’s stubble.

They kiss slowly, tentatively, almost as if they’re afraid to touch each other. When they break apart, Byleth cracks a smile and says, “Let’s just say you piqued my interest, too.”

Claude can’t help it; he laughs, in disbelief and euphoria and terror at the possibility of he and Byleth actually having something. It’s only the beginning, of course, and Claude’s not naive enough to think that they’re in love right now...but they _could_ be, someday. Claude could see himself falling for this kind, handsome young man. In the back of his mind, he thinks about all the things he keeps hidden from the world, all the things he longs to share. Perhaps one day, he’ll work up the courage to tell Byleth that he’s Almyran. Perhaps one day, he’ll let himself talk about his childhood while Byleth listens intently, never interrupting, only nodding.

Perhaps one day, he’ll ask Byleth to call him Khalid.

For now, though, Claude is content just to laugh with him, the thrill of a first kiss still buzzing in their bodies. The rest will come later—or maybe not, but Claude has always fancied himself a little bit of an optimist.


End file.
